1. Field of the Invention
The present invention generally relates to an image correction method, and more particularly to an image correction method which is applied to a scanner device.
2. The Related Art
Referring to FIG. 1, a conventional image correction method is applied to a scanner device. The scanner device generally includes a main case (not shown), a drive module 10′, an optical module 20′, an analog-to-digital converter 30′ and a memory storage unit 40′. The drive module 10′, the optical module 20′, the analog-to-digital converter 30′ and the memory storage unit 40′ are electrically connected and are assembled in the main case. The memory storage unit 40′ is capable of moving in the main case. The optical module 20′ includes an optical source 201′, a lens 202′ and an image sensing element 203′. The image sensing element 203′ is a charge coupled device (CCD) or a contact image sensor (CIS). A top of the main case is disposed with a scanning platform (not shown).
Usually, when a document is scanned by the scanner device, an image outputted by the scanner device has a nonuniform brightness. In order to make the image has a uniform brightness, the scanner device should correct the image by virtue of the image correction method. Steps of the image correction method are described as follows. At first, position the document which is ready to be scanned on the scanning platform of the scanner device. Then, the drive module 10′ drives the optical module 20′ to move to begin scanning the document. Specifically, the optical source 201′ shines on the document through the scanning platform to reflect a plurality of beams, then the beams are exactly focused on the image sensing element 203′ through the lens 202′ to form the image, and the image includes a plurality of image pixels. Later, the image pixels are converted into digital signals via the analog-to-digital converter 30′. Again, store the digital signals in a storage area of the memory storage unit 40′, and the digital signals are calculated by virtue of applying an interpolation method and a multiplication method so as to build a shading table. At last, the scanner device utilizes the shading table to perform a brightness compensation of the image.
However, in the process of building the above-mentioned shading table to perform the brightness compensation of the image by the image correction method, unpredictable spots or dust on the document will affect the build of the shading table to get an inaccurate shading table and further affect an image correcting effect. Meanwhile, in the process of building the shading table in the storage area of the memory storage unit 40′, the storage area of the memory storage unit 40′ is without being properly divided into corresponding areas that makes the digital signals irregularly stored in the storage area of the memory storage unit 40′. Thus, the scanner device needs to have the memory storage unit 40′ with a larger storage area that increases an image correction cost of the scanner device.